Sub-floor / sub-frame failure!!! Check your M Coupe today!

[Dextergregor]

Hi I just got an 08/2001 Z3 roadster 2.2i. Reading this thread I'm getting the sickening dealing that my car suffers from this problem. Does the problem manifest in the handling? I.e. a somewhat harsh feeling and sounding rear suspension? I ask because that's the way mine feels. I assumed this was because the shock absorbers on mine were shot. It seems I might be wrong.

PS. Merry Christmas everyone!

['Yadi]

Sorry to revive this older quote but question for CW if you're about?

I very occasionally get a creaking noise rather than a crack when setting off in the morning and lifting clutch/engaging drive.

I've associated it with cold mornings and assumed clutch or temperature thing going on - always listen out for it on the next journey (inevitably end of work going home) and it's never occured two trips in a row.

Was the squeak noise that led you to take out the sound deadening caused by the spot weld failure (and noise gone when they were repaired).

I do check the boot a few times a year and had the underside inspected when the car got some waxoyl in November but no signs of problems from that view either.





All I had was a a squeak/cracking noise occassionaly when setting off. I'd checked the diff bolts and anything else a few times. Also did check the boot floor but could see no signs of failure. It was only when I started stripping out the interior to try and narrow it down that could only think it was the boot floor making the noise. When I scraped the sound deadening off about 3 or 4 spot welds had failed above/left of the rear diff mount but it was very difficult to see and could only be seen INSIDE the boot with the deadening scraped off.

Mine was only a light failure, it was only the noise that attracted my attention. I think for those that fail worse the drivers just didn't noticed it as I can see when it fails worse like the cross-member starts to fall away from the chassis rail it will make a right racket.

If you don't have any noises on clutch/drive take-up in 1st I would guess it's fine.

[c_w]

Yes, the noise was there but I couldn't work out where it was coming from. It could be described as a creak, like dry rubber I suppose. It only did it on the initial take up of drive in 1st gear, *sometimes* going in to 2nd but not audible any other time. Conscious of the bootfloor issue it was something I check but didn't spot anything until I took the sound matting up that is bonded to the boot floor (with a heatgun etc). The crack was barely visible underneath, but with the matting off and cleaned up it's much easier to spot any fails inside the boot.

['Yadi]

thanks for the reply c_w. I'll make the heatgun job the next on my list then just to be sure.

Do folks replace the sound deadening material afterwards with the same sort of stuff (and if so can someone point me to a good source?) or use something different to deaden the noise that doesnt stick down so it's easier to check underneath in the future?

[c_w]

I used some Dynamat, when it's warmed up a bit you can use a small decorators roller to imprint it over the shape of the boot floor and it looks fairly factory. It needs something like this bonded to the metal (or brown bread bitument tape from ToolStation etc) otherwise I can imagine it resonating.

I would say a decent hairdryer would also soften it enough to scrape it off!!

[johnnyb]

I didn't replace the sound deadening matting and can't tell any difference. There's still plenty of sound insulation once the boards are back in.

[c_w]

Yea the extra foam insulation and boards will help but every car usually has this sound deadening over every flat panel to reduce resonance and other drone type noises - it doesn't help that the metal is so thin! I actually added some on the right hand side where it slopes down to the puncture kit.

[dave p]

found this write up with some pictures,

http://www.vorshlag.com/forums/showthread.php?t=8039

[indy]

bump as a reminder for everyone to check their boot floors!

[c_w]

Part nos for info;

The normal diff bracket is part no. 41118398664 and was around £12.18 a few years ago

There is also a "repair part" diff bracket part no. 41117033491 ~£188.70 which from diagrams consists of a diff bracket already attached to a length of cross-member. I'm not sure but this may fit up against the existing cross-memeber to double up the strength in this area. I didn't go for it due to the cost!